1. Field of the Invention
The present invention relates to polymer fine particles for a jet ink, process for producing the same, and a jet ink comprising as an essential component said polymer fine particles for a jet ink.
The polymer fine particles for a jet ink according to the present invention contain a colorant and have an average particle diameter in the range of 5 to 700 nm, a maximum diameter of at most 1000 nm, and a particle size distribution, at m value of shape parameter according to the Weibull distribution, of at least 1.3.
The polymer fine particles for a jet ink according to the present invention are stable in a dispersion medium such as water and the like, and are able to form a coating film at room temperature. Moreover, the aforementioned polymer fine particles form a coating film which is insoluble in acetone. In addition, the ink comprising the polymer fine particles according to the present invention displays a superior durability and is ideal for use in ink jet recording systems.
2. Background Art
The ink jet recording system, with no waste of ink and the ability to use standard paper, affords many advantages such as being economical, wherein high grade printing, in which coloring is easily accomplished, is possible with limited noise at the time of printing.
However, since aqueous inks primarily comprising water-soluble resins are mainly employed as the ink in the above ink jet recording system, conventionally, significant drawbacks exist when these inks are applied to practical use, such as generation of smudging of the printed matter due to water or sweat, frequent blurring of the printed copies, as well as an inferior durability and resistance to wear.
In order to improve these drawbacks, numerous experiments are being conducted which use a binder instead of the conventional water-soluble resin. For example, in Japanese Patent Application, First Publication No. Sho 58-45272, an ink is disclosed which comprises an aqueous medium and dye-containing polyurethane latex particles which are formed by means of adding a hydrophobic dye to polyurethane latex, previously prepared from a polyol and diisocyanate, which possesses particles of 0.01 to 1.0 microns in diameter, under the presence of an organic solvent such as an acetone-ethyl acetate mixed solvent or the like, and then mixing them.
Additionally, in Japanese Patent Application, First Publication No. Sho 62-95366, a method is disclosed for producing an ink by means of dissolving in a water-insoluble organic solvent, a polymer that is soluble in an organic solvent and an organic oil-soluble dye; the resultant mixture is then suspended in water, dried and redispersed into 0.3.about.1.0 micron fine particles which contain a dye to form the ink.
Furthermore, in Japanese Patent Application, First Publication No. Hei 6-145570, with regard to an ink for use in ink-jet recording which comprises a pigment and high polymer dispersing agent, and is prepared using a water-insoluble resin emulsion, such as a polyacrylic ester emulsion, a method is disclosed for obtaining a high-grade ink which is free of smudging by means of specifying the compositional ratio thereof.
Unfortunately, these aforementioned processes do not exhibit sufficient improvements with regard to the conventional drawbacks.